Request for review: 8004834: Add doclint support into javadoc

[Jonathan Gibbons]

Build folk,

We will soon want to push changes into TL to enable doclint support in 
javadoc. This will require a minor build change until we can fix up 
(lots of) errors in our javadoc comments.  The problem is that because 
of the many errors in our doc comments, javadoc will now exit with a 
non-zero exit code, unless we either disable doclint, for now, or ignore 
exit codes.

The interim solution is to disable the use of doclint when generating 
docs during the build, by specifying a new option -Xdoclint:none.

Although there is only one change, it appears in two places, for the old 
and new build:
The webrevs are here: http://cr.openjdk.java.net/~jjg/8004834/

The langtools part of the webrev, enabling doclint, will be reviewed 
separately.

-- Jon